Influence of different templates on the textured Bi 0.5(Na 1− xK x) 0.5TiO 3 piezoelectric ceramics by the reactive templated grain growth process

Abstract

One-dimensional TiO 2 whiskers were used first time as templates to fabricate grain-oriented Bi 0.5(Na 1− x K x ) 0.5TiO 3 ( x=0.15) (BNKT) piezoelectric ceramics with the reactive templated grain growth process. The influences of sintering temperature and the template concentration on the orientation of BNKT were investigated. The orientation factor along ( h 0 0) direction was only 26.41% since the fibrous TiO 2 particles on the surface were aligned along the extrusion direction while many randomly oriented particles were in the middle of the rods. The reaction and crystal formation of BNKT ceramic from fibrous TiO 2 templates is a dissolution–recrystallization process on its surface and the dissolution of fibrous TiO 2 templates is detrimental to the grain orientation. The orientation factor of more than 70% was obtained successfully when the plate-like Bi 4Ti 3O 12 was used as the templates using a tape casting process. The reaction and crystallization of the two kinds of templates in the whole sintering process were discussed and the grain orientation mechanism was also elucidated in this paper.